Definition & Overview

A fever, in itself, is not considered an illness, but it is usually a symptom of a medical condition or infection. Fever is the body’s natural response as it tries to fight off viruses or infections. A portion of the brain called the hypothalamus controls the body’s temperature. In response to certain illnesses or viruses, the hypothalamus raises the temperature to increase the immune system’s ability to combat the infection.

What is the normal body temperature?

In a healthy adult, the normal temperature can be identified in four areas: the rectum, the mouth (oral), the ear (otic), or the armpit (axillary). A normal rectal temperature range is 34.4 to 37.8 °C while a normal oral temperature is 33.2 to 38.2 °C. On the other hand, a normal otic temperature is 35.4 to 37.8 °C, and axillary body temperature is 35.5 to 37.0°C.

However, it is important to note that a normal body temperature relies on other factors such as sex, age, the current level of activity, and other things. An elevated temperature may not necessarily mean a fever. For instance, when a person is exercising, the body’s temperature has a tendency to rise but it will still be considered as normal. However, in some people, even a normal temperature range can already be considered as a fever. Thus, it is important to note the baseline temperature of an individual before considering a fever.

Fever classifications

Fever can be classified into different categories according to its duration or temperature level. The common categories of fever are the following:

  • Hyperpyrexia: When the body temperature reaches or exceeds 41.5°C. Such cases are considered emergencies.
  • Chronic Fever: When a fever lasts for over three days or frequently occurs.
  • Intermittent: When the body temperature rises and drops to normal levels in one to three days.
  • Remittent: Is used to describe a fever that returns at regular intervals.
  • Constant Fever: Describes a low-grade fever that neither increases nor decreases over one degree in a 24-hour period.


Fever that is not associated with serious medical conditions is typically caused by:

  • A viral infection
  • Heat exhaustion
  • A bacterial infection
  • Extreme sunburn
  • Inflammatory conditions
  • Immunizations or vaccine shots
  • Certain drugs and antibiotics used to treat seizures and high blood pressure

When should you seek medical assistance?

It is important to remember that a fever is a symptom of a medical condition, such as a bacterial or viral infection, diseases, and other life-threatening conditions. In most cases, the fever itself will not require treatment, but the underlying condition. However, if the fever interferes with normal body functions, it is best to seek medical attention immediately. These cases can be, but are not limited to:

  • Difficulty of Breathing
  • Frequent Vomiting
  • Abdominal Pains
  • Bloody Stool
  • Chest Pains
  • Severe Headaches
  • Rashes
  • Hyperthermia
  • If the patient is not responding
  • If the patient is agitated or confused for no reason

Once at the hospital, the doctor will require specific information to make a proper diagnosis. You will be asked as to when the fever started, if you have allergies, or if you’re taking medications. The doctor may also ask about other symptoms or any other known illnesses. Depending on the result, the doctor may order different examinations and laboratory tests to pinpoint the exact problem.

Home Remedies and Treatment

If the fever does not result in the situations described above, some over the counter medications can help bring down a person’s temperature. Ibuprofen and acetaminophen are both effective in reducing fever. Some people may still have aspirin in their homes, but this is not the drug of choice when it comes to treating fevers. Aspirin should not be given to children or teens as it has been proven to cause other types of medical conditions.

If the fever returns after taking medications, it is best to seek medical attention to properly identify the cause of the fever. Taking ibuprofen and acetaminophen for long periods may have side effects and may cause liver failure over time.

In general, people with a known illness should consult a physician instead of trying home remedies, as the fever may be a sign of a worsening condition. If the fever is caused by hyperthermia, heat stroke, or heat exhaustion, neither of the aforementioned medicines will have any effect. The patient will need to be cooled immediately by first removing him/her from a hot environment, removing any clothing, and then using a wet sponge over the body to bring down the temperature. This will help in an emergency, but medical assistance should still be sought right away.

Dehydration may also cause a fever. In this case, the patient will need to be hydrated immediately. Cooling the patient with wet sponges can make matters even worse in this situation since not only will the patient feel uncomfortable, the technique can also cause shivering and may even increase body temperature if the underlying condition is an infection.


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